GeoTools transform from CRS in meters to CRS in degree (WGS84)-CodePudding

I am trying to use GeoTools to transform between two coordinate systems, one in meter and the other in degree, but no matter what i try the converted values are not correct. I have tried to follow other examples using the same code, but for some reason it fails to convert between these two coordinate systems: [EPSG:3044] -> [EPSG:4326] (WGS 84)

I am parsing the WKT for both CRS and then transform it using GeoTools - below is my current code, together with my results:

EDIT The source code has been updated to reflect the output of using WKT and the internal CRS decoder.

val sourceCRS = CRS.parseWKT(
  """PROJCS["ETRS89 / UTM zone 32N (N-E)",
    |    GEOGCS["ETRS89",
    |        DATUM["European_Terrestrial_Reference_System_1989",
    |            SPHEROID["GRS 1980",6378137,298.257222101,
    |                AUTHORITY["EPSG","7019"]],
    |            TOWGS84[0,0,0,0,0,0,0],
    |            AUTHORITY["EPSG","6258"]],
    |        PRIMEM["Greenwich",0,
    |            AUTHORITY["EPSG","8901"]],
    |        UNIT["degree",0.0174532925199433,
    |            AUTHORITY["EPSG","9122"]],
    |        AUTHORITY["EPSG","4258"]],
    |    PROJECTION["Transverse_Mercator"],
    |    PARAMETER["latitude_of_origin",0],
    |    PARAMETER["central_meridian",9],
    |    PARAMETER["scale_factor",0.9996],
    |    PARAMETER["false_easting",500000],
    |    PARAMETER["false_northing",0],
    |    UNIT["metre",1,
    |        AUTHORITY["EPSG","9001"]],
    |    AUTHORITY["EPSG","3044"]]""".stripMargin)

val targetCRS = CRS.parseWKT(
  """
    |GEOGCS["WGS 84",
    |    DATUM["WGS_1984",
    |        SPHEROID["WGS 84",6378137,298.257223563,
    |            AUTHORITY["EPSG","7030"]],
    |        AUTHORITY["EPSG","6326"]],
    |    PRIMEM["Greenwich",0,
    |        AUTHORITY["EPSG","8901"]],
    |    UNIT["degree",0.0174532925199433,
    |        AUTHORITY["EPSG","9122"]],
    |    AUTHORITY["EPSG","4326"]]
    |""".stripMargin)

val source = CRS.decode("EPSG:3044");
val target = CRS.decode("EPSG:4326");

val originalCoordinate = new Coordinate(5293975.04, 959436.64)
// WKT
val coordinateWKT = new Coordinate()
val wktTransform = CRS.findMathTransform(sourceCRS, targetCRS, true)
JTS.transform(originalCoordinate, coordinateWKT, wktTransform)
// EPSG
val coordinateEPSG = new Coordinate()
val epsgTransform = CRS.findMathTransform(source, target, true);
JTS.transform(originalCoordinate, coordinateEPSG, epsgTransform);
// Output
System.out.println(s"Original: ${originalCoordinate}")
System.out.println(s"EKT: ${coordinateWKT}")
System.out.println(s"EPSG: ${coordinateEPSG}")

And my input and output coordinates are:

Original: (5293975.04, 959436.64, NaN)
EKT: (48.79550725975144, 6.678848738740256, NaN)
EPSG: (47.63578358581114, 15.117187455070956, NaN)

CodePudding user response：

So the correct transformed coordinate would be: (56.4336819°, 4.1353377°)

Maybe your source coordinate is inaccurate because it is not in the area where the coordinate system is used.

From epsg.io:

Area of use: Europe between 6°E and 12°E: Austria; Belgium; Denmark - onshore and offshore; Germany - onshore and offshore; Norway including - onshore and offshore; Spain - offshore

Your coordinate is east of Africa, in the Indian Ocean.

If I'm using for example coordinates from Austria, I get the following output (in Java):

CoordinateReferenceSystem source = CRS.decode("EPSG:25832"); 
CoordinateReferenceSystem target = CRS.decode("EPSG:4326");
Coordinate coordinate = new Coordinate(959436.64, 5293975.04);
// when you are using EPSG:3044, you have to change x and y: 
// Coordinate coordinate = new Coordinate(5293975.04, 959436.64);
MathTransform transform = CRS.findMathTransform(source, target, false);
JTS.transform(coordinate, coordinate, transform);

System.out.println(coordinate);  //(47.63578358581114, 15.117187455070956, NaN)

And that's the same result as from epsg.io. Note that I'm using EPSG:25832 instead of EPSG:3044.